Apparatus for sewer treatment to kill tree roots and other organic growth therewithin

ABSTRACT

A composition for killing plant roots inside sewers, comprises an alkali metal alkyl dithiocarbamate in an amount of about 30%, a biodegradable liquid nonionic surfactant in an amount of about 12%, and water making up the remainder. One method for treating the sewer pipes comprises coating the inside wall of the pipe and any roots or other growth inside the pipe with the composition in the form of a foamy film by spraying it thereon or on the upper portion thereof, as from a continuously moving device. Preferred apparatus for so treating the sewer pipes comprises a sled having bottom skid means, a low center of gravity and a spray system mounted on said sled having generally upwardly directed nozzles, and means for pulling the sled through a pipe while supplying it with the composition under pressure. Another method comprises soaking with the solution diluted to about 2% of the methyldithiocarbamate, this being done by plugging the pipe and filling the pipe above the plug with the diluted solution. Special plugging apparatus is described.

United States Patent Home APPARATUS FOR SEWER TREATMENT TO KILL TREEROOTS AND OTHER ORGANIC GROWTH THEREWITHIN inventor: Frederick F. Horne,Carmel Valley.

Calif.

Assignee: Airrigation Engineering Company,

Inc., Carmel Valley. Calif.

Flied: Apr. 30, 1973 Appl. No.: 355,808

Related US. Application Data Division of Scr. No. 122.738, March l0.l97l. Pat. No. 3.74l.807. which is a continuation-in-part of Ser. No.850.32l. Aug. 6. I969, abandoned. which is a continuation-in-part ofSer. No. 760.822. Sept. 19. I968. abandoned.

[ Apr. 29, 1975 Erickson [57] ABSTRACT A composition for killing plantroots inside sewers. comprises an alkali metal alkyl dithiocarbamate inan amount of about 30%. a biodegradable liquid nonionic surfactant in anamount of about 12%, and water making up the remainder. One method fortreating the sewer pipes comprises coating the inside wall of the pipeand any roots or other growth inside the pipe with the composition inthe form of a foamy film by spraying it thereon or on the upper portionthereof. as from a continuously moving device. Preferred apparatus forso treating the sewer pipes comprises a sled having bottom skid means, alow center of gravity and a spray system mounted on said sled havinggenerally upwardly directed nozzles, and means for pulling the sledthrough a pipe while supplying it with the composition under pressure.Another method comprises soaking with the solution diluted to about 2%of the methyldithiocarbamate. this being done by plugging the pipe andfilling the pipe above the plug with the diluted solution. Specialplugging apparatus is described.

9 Claims, 14 Drawing Figures PATENTED PRZ E 3.880.176

sum 30F 3 'IIIIIIIIIA V'I'I' i FIG- H644 I so FIG-12 APPARATUS FOR SEWERTREATMENT TO KILL TREE ROOTS AND OTHER ORGANIC GROWTH THEREWITHIN Thisis a division of application Ser. No. l22,738 filed Mar. 10, 1971, nowU.S. Pat. No. 3,741,807, which was a continuation-in-part of applicationSer. No. 850,321 filed Aug. 6, 1969 now abandoned, which was acontinuation-in-part of application Ser. No. 760,822 filed Sept. 19,1968, now abandoned.

This invention relates to the treatment of sewers and other conduits tocontrol plant growth therein. It relates to novel compositions for usein the sewers to kill root growth therein; to novel and effectivemethods for applicati on of this composition; and to apparatus by whichthe composition may be applied.

Many materials for controlling plant root growth in sewers and otherdrainage conduits have been tried, such as copper sulfate, which hasbeen the most widely used chemical for this purpose over many years, butnone of them has proven satisfactory in the long run. One of the mainproblems has been the fact that most tree roots come down from above,and such roots have not been affected by the treatments tried. Thereasons for this ineffectiveness have been twofold: l the chemicals havebeen contained in and confined to the sewer water in the lower part ofthe pipe and therefore do not even touch the roots that lie above thesewer water; (2) such chemicals require a relatively long exposure tothe roots to be effective, so that the only roots killed are those whichremain for a long enough period in contact with the water containingsuch chemical agents. To explain further, sanitary sewers are designedto transport waste water at much less than the capacity of theirconduits; hence, the waste water is normally in only the lower part ofthe pipe; thus, the copper sulfate and other herbicides and fungicidescarried in the waste water under normal flow could be effective only inthat lower part of the pipe where the roots may be in contact with thesewer water, and not elsewhere. However roots entering from above tendto die anyway when they reach the normal water flow line, due to thelack of oxygen in the sewage; these dead roots have practically noabsorptive ability, but roots continue to grow above the flow line andto occupy and till the major area of the pipe, eventually resulting inplugging. The prior art treatment materials may be potentially effectiveon any tree root which enters the sewer from below, but lack of oxygengenerally prevents this from happening; so this limited effectivenesshas been insufficient to prevent tree roots from plugging sewers. Nocomposition carried by the sewer waste water has been able to keep theentire pipe free from roots, nor to rid the pipe from all roots.Moreover, no sufficiently effective method of sewer pipe treatment forthis purpose has heretofore been found.

An excellent material for killing tree roots is sodiummethyldithiocarbamate, a chemical heretofore used successfully as a soilfumigant and for some other things, but it did not prove to be aseffective in sewers as one might expect; the vapors alone proved to berather ineffectual. It was proposed that a chemical fireextinguisherfoam be used as an extender or carrier, and such chemical foam with theliquid fumigant entrained was injected into sewers; by the expansionpressure exerted, the fire-extinguisher foam was forced along theconduit and as the foam disintegrated, active gaseous fumigant wasreleased. improvement was, in

deed, obtained by this expedient, but unfortunately this Improvementrequired the conduit to be completely filled under expansive foampressure in order to distribute the active fumigant to the surfaces tobe treated, and this required extremely large volumes of both thechemical fire-extinguisher foam and the active agent, as well aspressure to push the foam through the pipe. Thus, that process was tooexpensive for general use. Moreover, the chemical fire-extinguisher foamitself tended to block the sewage flow, so that the sewer had to betaken out of service for extended periods during this treatment.Further, the charging into the pipes of the fire-extinguisher foam withthe entrained active agent was a time-consuming operation, and the laborcost was not economically practical for large diameter or long conduits,especially when that cost was added to the materials cost of the largevolume of chemical foam extender needed. Even then, many roots were notkilled and remained.

Other investigations showed that, when sodium methyldithiocarbamate wasintroduced by spraying the pipe interior with a simple water solution,it tended to decompose too quickly from the water present to be Also,effective. Aslo, the water solution of the active chemical readily randown the pipe walls and quickly became part of the sewage flow,bypassing the roots above it. These investigations led me to believethat organic slime and other soils and greases were tending to protectmany tree roots from surface absorption and treatment, so that they werenot significantly damaged by what otherwise might be consideredintensive treatment. Furthermore, the roots appeared to be protected inmany instances by outer cell walls rich in cutin and suberin, which didnot significantly imbibe either water or the fumigant solution in water.A closed television circuit which was lowered into sewers enabled thetaking of pictures from outside the pipe as well as displaying an imageof what was inside the sewer, and these pictures showed that many suchroots were not killed even after very intensive treatment by watersolutions containing sodium methyldithiocarbamate.

The present invention provides a solution to the problem. All rootswithin the sewer are killed, no matter from what direction they come andno matter at what level the waste water flows. Moreover, a new andeconomical use of the composition of this invention, makes it possibleto kill these roots without killing or even damaging the same or otherroots outside the sewer and without damaging the plants from which theroots come. However, to give longer protection, it is also possible, ininstances where the joints of the pipe are damaged or leak to extend thekilling action somewhat beyond the pipe interior, thereby delaying theregrowth considerably, still without substantially damaging the plants,because the material used herein is not a systemic plant poison.

Even more important, my new composition penetrates the cutin and suberinof the root walls, which are impermeable to untreated water, and carriesthe active material inside the root cells, so that the toxic effect isgreatly enhanced. When used as a spray, my invention provides a novelsmall-bubble foam, which adheres to the roots. When used in a soak, moredilute solutions are quite effective. My new composition acts even onroots and other growths which are covered with slimes and greases, andit also cleans the roots and the pipe while killing these biologicalgrowths and the roots.

metal alkyl dithiocarbamates usable in this invention and their formulasare:

sodium N-methyl dithiocarbarnate sodium N- ethyl dithiocarbamate sodiumN- isopropyl dithiocarbama to sodium N-propyl dithiocarbamate sodium N-allyl d ithiocarbamate In each of the above, potassium may be substitutedfor sodium. So may other alkali metals, but the sodium and potassiumcompounds are the cheapest, the most soluble, and probably the best. Thefirst compound named above, also called simply sodium methyldithiocarba- 3O mate is the most volatile and is usually preferred.

A preferable class of surfactants usable in this invention is the alkylaryl polyether alcohols and the ethers thereof. For example, anoctylphenoxyethanol, such as a water-soluble iso-octyl phenoxy ethanolcontaining 10 moles of ethylene oxide (Triton X-100) has been provedvery effective. Another alkylaryl polyether alcohol is Retzanol NPlOO,of Retzloff Chemical Co, a nonyl phenoxy polyoxyethylene ethanol, aclear liquid with a pour point below 0C, a specific gravity of 1.06 atC, soluble in water. Another is Tergitol NPX (Union Carbide)a nonylphenyl polyethylene glycol ether.

By adding the surfactant in amounts of about l2/2% (one eighth) of thevolume of the regular fumigant mixture (a water solution having anactive ingredient rating of about 36%, meaning a 36% aqueous solution offor example, sodium methyldithiocarbamate), a preferred concentrateformulation is obtained wherein the active thrice as much of themethyldithiocarbamate as of the surfactant, water making up theremainder. Other alkaii metal alkyl dithiocarbamates are used in thesame amounts.

Use may be by spray or by soaking, and for actual use. more water isadded to the concentrate.

For spray application the concentrate is preferably diluted by threeparts of water to one part of concentrate. The diluted spray material isthus about onetwelfth sodium methyldithiocarbamate and aboutonethirtieth surfactant, and about nine-tenths water. This composition,when sprayed on or toward the sewer walls forms a foamy film that killsor materially inhibits the growth of all plant roots and other organicgrowth in the interior of the sewer. The surfactant in the spraycomposition does several things: (1) The surfactant acts to maintain theactive fumigant for a sufficient time in an active foam state on thepipe and root surfaces; (2) it provides the foam, which adheres well toall surfaces instead of running down and dripping off ineffectually, aswould a water spray; (3) the surfactant Na-s-i-Nii-ca Na- S-g-NH- CH CHCH removes the coatings of slimes, greases, soaps, and dirt that coverand protect the roots; and, (4) it holds the fumigant on and near thecleaned roots and surfaces, where the fumigant can be most effective. Asa result, only about one-sixth or one-seventh or even less of the alkalimethyldithiocarbamate is used as when fireextinguisher foam is used tofill the pipe, while the re sults are far, far more effective. Only thesurfaces need be coated with the foamed fumigant spray solution, and inthis invention that can be done quite efficiently.

In another treatment according to this invention, thefumigant-surfactant concentrate is further diluted, down to about one ortwo percent fumigant concentration, and then a length of the sewer pipeis filled and soaked. Here, again, the effectiveness is quite differentfrom filling a sewer pipe with a water dilution of the fumigant alone atthe same fumigant concentration. The surfactant acts to clean and exposethe roots while the fumigant simultaneously attacks them. Penetration isassured by having both the surfactant and fumigant simultaneouslypresent. The biological slimes, fatty acid soaps and greases, etc., areeffectively emulsified and dispersed into the waste water flow, and theroot cells are destroyed, causing the roots to decompose and slough off.By employing a pair of plugs and working with gravity from an upperlevel down, the same solution can be used in several successive soakingoperations, thereby economizing in material, and for this purpose novelplugging apparatus and systems have been developed.

Especially in the soak-treatment, but also in the spray treatment,growth inhibitors may be incorporated to cause greater root die-back andto prolong the time during which no re-treatment is required. For thispurpose, the only limitations on the use of any particular growthinhibitor (growth inhibitors being a well-known group of herbicides) arethat it not be systemic, so as to poison the entire plant and kill it(though they may even be systemic to a degree, i.e., to kill roots backa few inches or so) and that there be no chemical reac tion between thegrowth inhibitor and the fumigant or surfactant so as to nullify any ofthe ingredients. For example, 4-(methylsulphonyl)-2,6-dinitro-NN-dipropylaniline, trifluralin (an approved common name for 2,6-dinitro-NN-dipropyl-4-trifluoromethylaniline dichlobenil (an approvedcommon name for 2,6 dichlorobenzonitrile), and S-(0,0-diisopropylphosphorodithioate) of N (2 mercaptomethyl) benzenesulfonamide) have allbeen tried and have been found to give very satisfactory results, withroot killbacks a few inches beyond the pipe walls. Also, where a pipehas breaks or its joints are broken or leak, the soak treatment sets uphydraulic pressure and, in conjunction with the growth inhibitor,extends the treatment beyond the interior of the pipe and considerablyinhibits or delays regrowth, yet without significant damage to the plants themselves.

In some instances, it may be desirable to add a further treatmentsimultaneously to rid the sewer of insects, such as spiders, roaches,and sewer flies. Some of them may be killed by the fumigant, but otherchemieals may be added to the solution to obtain a residual control, solong as they do not react with the other ingredients in a way thatdiminishes the activity and efficiency of any of the treating materials.Chlordane, DDT, diazinone, roach wettable powders and so on, may beadded in effective amounts, as may some specific fungicides, if desired,so long as the added chemicals do not detrimentally react with thefumigant or surfactant (a growth inhibitor, if present) in the originalsolution.

My new composition is nonsystemic, so that it does not harm the plantsthemselves, but it does control all the roots which are in sewer mainsor other conduits so treated, and it also helps to control any fungi, orbacteria such as produce slimes, and fatty acids. In this way, thegeneration of hydrogen sulfide in the sewers is reduced, and the rootsand organic deposits are handled so effectively by my new compositionthat substantially no harmful residue remains. The gaseous fumigantitself is dissipated within a few hours, and the composition as a wholeis readily biodegradable. Moreover, the biological slimes, fatty acids,etc., are effectively emulsified and dispersed into the waste waterflow, and the root cells that are destroyed result in the decompositionand sloughing off of the roots, which are thus carried down the sewer.

To illustrate the biological effectiveness of the invention, a sample ofthe solution, diluted to (20.4% active sodium methyldithiocarbamate) wasbioassayed in comparison to the standard solution (32.7% activematerial). The procedure followed was to dilute each solution with threeparts water and then place 0.1 ml of the diluted solution into vialscontaining 9.9 ml of sterile Difco bacto-malt broth or bacto-nutrientbroth. The broth was then inoculated with spore suspensions ofAspergillus niger, Penicillium italicum, Escherichia coli, andStaphylococcus aureus. The vials were sealed and, after one week,observations were made on the growth of the organisms in the vial. Allvials inoculated with both formulations remained clear and no growth ofthe organisms occurred. The growth of the fungi and bacteria inuntreated vials was heavy.

As stated earlier one method of application includes spraying my newcomposition, with the concentrate di luted by about three parts of waterto one of the composition. The spray impinges a small bubble foam uponthe surfaces inside the pipe by directing the spray upwardly whilemoving the spray apparatus, preferably at a substantially constant ratethrough the pipe and while maintaining the spray nozzles in a properorientation, so that the spray is directed upon the upper portion of thepipe and roots and slimes and other growth, above the normal level ofthe waste water flow. Much of the foam adheres where it impinges, whilesome of the material runs down the pipe walls into the waste water andis also effective there. The small bubble foam slowly releases theactive fumigant and fills the pipe with the toxic vapor, so that thewhole inside volume is treated effectively with the fumigant.

The spraying apparatus of the invention may include a set of pressuretanks for the solution of this invention interconnected with an inletmanifold and suitable valves which control a gas supply and terminate inthe side opening of a tee connection. The tanks may be interconnectedthrough a discharge manifold to a reelmounted pressure hose through anappropriate swivel fitting. A sled-mounted spray assembly of a size ableto pass through the sewer is equipped with a pair of atomizer nozzleswith orifices, one leading forward. the other to the rear, which applythe solution at a suitable rate, such as a quarter of a gallon ofdiluted solution per minute at a pressure of a hundred pounds per squareinch. The sled-mounted spray assembly may be connected to the pressurehose, a valve opened (preferably at the sled), and the spray assemblyand hose may, while spraying, be drawn through a sewer by a cable orpower rod to an end of the desired run, which may be the next manhole;then the valve may be closed, the sled may be removed, and th s hosewithdrawn. The mixture automatically forms the desired surface-activefumigant, and the spray places the small-bubble foam in contact with allportions of the pipe interior and with all roots inside the pipe. Thesurface film stays as a foam for a time long enough for full contact andactivity by the chemicals involved, without remaining longer thannecessary.

Other objects and advantages of the invention will appear from thefollowing description of a preferred form thereof.

In the drawings:

FIG. 1 is a view in side elevation of a trailer-mounted apparatuscomprising part of a sewer-spraying apparatus embodying the principlesof the invention.

FIG. 2 is a view in front elevation of the apparatus of FIG. 1.

FIG. 3 is a top plan view of a sled and nozzle assembly that may be usedin conjunction with the apparatus of FIGS. 1 and 2 in this invention.Alternative "on" and off" positions of the shut-off valve are shown, oneposition being shown in solid lines, the other position being shown inbroken lines.

FIG. 4 is a view in side elevation of the sled and nozzle assembly ofFIG. 3.

FIG. 5 is a view in vertical cross section of a pipe afflicted withroots which, if they grow too massive, will eventually plug the pipe orbreak the pipe joint, causing infiltration.

FIG. 6 is a similar view showing the sled moving through the pipe ofFIG. 5 and spraying it.

FIG. 7 is a fragmentary view in side elevation and in section takenalong the line 7-7 of FIG. 6 showing the spray acting.

FIG. 8 is a view on a smaller scale than FIG. 7 showing the assembly ofFIG. 3 passing through the pipe and how it is being pulled by cable orpower rod. The pipe is broken in the middle to conserve space.

FIG. 9 is a view somewhat similar to FIG. 8 of a modified form of theinvention in which a combination cable-hose assembly is inserted throughone manhole and pushed to the next manhole, where it is attached to asled assembly generally like that of FIG. 3.

FIG. 10 is a view similar to FIG. 9, showing the apparatus of FIG. 9 inuse.

FIG. 11 is a view similar to FIG. 10 with a modified form of nozzle onthe end of the combination cablehose.

FIG. 12 is an enlarged fragmentary view in elevation and in section of acable-conduit combination in which a coil spring encircles a relativelythin-walled plastic conduit.

FIG. 13 is a view similar to FIG. 12 of a modification of the previousunit in which a coil spring cable is inside the conduit.

FIG. 14 is a view of the cable-conduit combination of FIG. 13 with asimple nozzle arrangement attached to one end thereof for use insituations like that of FIG.

The spray method of the present invention involves coating all surfacesinside a pipe to be treated. with an atomized dilute water solution ofthe fumigant vapor and surfactant. so that there is an active foam onall the surfaces inside the pipe. including the pipe surfaces, the rootsurfaces. and the slime-covered surfaces. This coating is donepreferably by directing a spray of the material toward the upper portionof the pipe so as to get direct impingement on the roots that tend togrow in the upper portion of th pipe above the normal liquid flow, anarea which i .ore difficult to treat than those areas that can bereached by active agents in the waste water or sewage flow. The activematerial is deflected and flows down along the pipe walls and othersurfaces to cover all the surfaces, including that of the waste water.with foam sufficient for active treatment of the slime. grease and rootsin the bottom portion of the pipe. Immediately. the nonionic surfactantcarries the alkali metal alkyldithiocarbamate through the waterexcludingouter walls of the root into the root and kills the cells therein, andif the root is coated with slime or grease, the surfactant penetratesthat too and washes it off. always carrying the fumigant with it. Thesmall bubble foam of this invention has been found to be more stable andto adhere to the surfaces of the roots and other organic material longerthan can largebubble foams, such as fire-extinguisher foam. Treatment ofthe roots thus is much more efficient because the toxic vapor is held inclose proximity to the root cells or surfaces, and also because thefoam-forming surfactant is active in cleaning, exposing and penetratingthe surfaceswhich fire-extinguisher foam is un able to do.

This spray method may be accomplished with the aid of the apparatusshown in FIGS. 1-4, some parts of which are moved along inside the pipewhile the other parts remain outside. FIGS. 1 and 2 show the outsideportion of a preferable apparatus, including a trailer 10 having a pairof wheels 11 and carrying a reel 12 of hose l3 and also a set of fourtanks 14, l5, l6 (and one not seen in the drawings), which contain thediluted active solution. One end of each of the tanks 14, 15, 16 (andthe one not shown) may be connected by a tee 17 and a pressure gauge 18to an inlet manifold 20, and the tanks opposite ends may be connected byconduits 21 to an outlet manifold 22. The manifold 22 may be connectedby a central conduit 23 that extends through the reel 12 to the hose 13and by the hose 13 to the nozzles 31 and 32 on the sled 30, shown inFIGS. 3 and 4.

The pair of atomizer nozzles 31 and 32 are both located approximately atthe middle of the sled 30 at a sled manifold 33. The sled 30 has a skidbase 34, which may be a generally semi-circular shell, for example.defining the lower surface of the sled with front and rear upward ends35 and 36, and the center of gravity is kept low, so that the sled 30rides low along the lower surface of the pipe 25; consequently, thesprays 37 and 38, from the nozzles 31 and 32 are directed generallyupwardly, as shown in the drawings. Curved guard rods 39 extend acrossthe sled 30 and protect the manifold 33 and nozzles 31 and 32, helpingalso to support them. The root-treating liquid is sent into thesled-borne manifold 33 at sufficient pressure, e.g., I I0 to I25 psi, toemit the desired sprays 37 and 38, as by impelling the liquid bynitrogen or other suitable gas under high pressure. A shut-off valve 40is provided closely adjacent the manifold 33, with a lever 41 that maybe actuated from the street above by pulling on a chain 42 to open thevalve 40 or on a cable 43 to close the valve.

As shown in FIGS. 5 and 6, the root growth 26 occurs only at joints orcracks and tends mainly to be in the upper portion of the pipe 25 (sincegenerally roots cannot live in the oxygen-depleted waste water in thelower portion). This growth 26 is contacted, by the sprays 37 and 38,and the surfactant acts immediately to remove grease, slime. and otherthings that might slow the toxic effect upon the roots by the fumigant.while also helping to form a surface-active film in the nature of asmall bubble foam on all surfaces inside the pipe 25. The atomizedfumigant solution then is in contact with the roots 26 and acts torelease its fungicidal and phytocidal chemicals, largely as vapors;these act in a nonsystemic manner to kill only the root portions towhich they are actually exposed in the sewer.

The sled 30 may have two rings 44 and 45, one at each end. The ring 44may be attached to a cable or wire rope 46 which is used to pull thesled 30 through the pipe 25. The ring 45 may be attached to a drag line47 to enable pulling back on the sled 30, should it encounter anobstacle in the pipe preventing its forward movementv The cable 46 maybe secured to the end of a conventional mechanical rodding device afterthe rod is driven from one manhole 48 to the next manhole 49. There. thesled 30 with the cable 46 attached to the rod is pulled back through thepipe 25 by the cable 46 and power rod from the manhole 49 to the manhole48, and the hose 13 and dragline 47 follow along, the hose 13 unreelingas it goes.

The chain 42 is pulled to move the lever 41 to open the valve 40, andthen the nozzles 31 and 32 are fed continuously with the treatingsolution, while the sled 30 is moved through the pipe 25 at asubstantially constant rate of speed and with substantially constantoutput. Thereby, the full reaction is obtained and the material isdispersed and acts.

When the sled 30 reaches the manhole 48 and is pulled out by the cable46, it is detached from the hose l3, and the hose 13 and dragline 47 arethen pulled back through and out from the manhole 46. The pipe 25 andall other surfaces between the manholes 48 and 49 have then been coatedwith a foamy film of small bubbles, which includes the fumigant andsurfactant. The fumigant attacks the roots and organic growth generally,and the surfactant carries the fumigant into the inner cells of theroots and attacks grease, slime, and din, freeing it from the pipe andfrom roots and exposing them, rendering the roots liable to attack bythe fumigant, which displaces the normal sewer atmosphere and is alsoheld in the small bubble foam.

In some installations the power rod and cable 46 and dragline 47 may notbe needed. In which case, the power rod and cable 46 may be replaced bya coil spring cable and hose combination 50 as shown in FIG. 9, the coilspring cable 51 serving to carry the hose 52 through the pipe and toreturn it and the sled 30 while the spraying is done. It is feasible inshort side-lines, and especially small-diameter ones, to use a coilspring cable hose unit 50, wherein the hose 52 is surrounded by the coilspring cable 51 and is provided with a suitable spray device 53 (FIGS.11 and 14) at one end, and to send that out to a desired length and thento spray while pulling the cable-hose unit back.

The cable-conduit unit 50 may be like that shown in FIG. 12 in which acoil spring cable 51 is employed with a thin walled plastic conduit 52inside it. On the other hand, it may be a unit like the unit 55 shown inFIGS. 13 and 14 in which a coil spring cable 56 is inside the conduit57. In fact, as shown in FIG. 15, a conduit 58 may be molded around aclose-wound coil spring cable 59, the rubber filling the outer cavitiesbetween successive coils. The basic point here is that the cable andconduit are made a unit so that it becomes possible to do the pullingwith the very unit which is applying the liquid.

The structure may be used as shown in FIGS. 9 and by inserting thecable-hose unit 50 into a pipe 60 via a manhole 61 and driving the cableforward to the next manhole 61, then attaching to it the sled 30 andthen, as in FIG. 10, pulling the sled 30 along while spraying and thenremoving the sled 30 from the first manhole 61.

Another way of using this device with results that are satisfactory forsome uses is to install the simple nozzle 53 on the end ofacable-conduit unit 50 or 55 and then pushing the unit 50 or 55 whereverdesired and then pulling it back while spraying. In such instance, ifthe spray is such that it cannot be maintained in a stable position, itmay be provided with openings all around so that the spray will reachall portions of the pipe. Naturally. this is somewhat less efficientthan with the use of the sled as given before, but it is a feasible wayof op erating in situations where the sled cannot be used.

To those skilled in the art to which this invention relates, manychanges in construction and widely differing embodiments andapplications of the invention will suggest themselves without departingfrom the spirit and scope of the invention. The disclosures and thedescription herein are purely illustrative and are not intended to be inany sense limiting.

As pointed out earlier, the spray method has been given extensive andsuccessful trials in city sewers and has worked. One city that uses aclosed-circuit television camera inside the sewers with a screen outsidethe sewers has been able to see the effectiveness by comparisons of thestate of the sewer before application with its state afterwards.

I claim:

1. Apparatus for treating root-infested sewer pipes including incombination a sled having a bottom skid for engaging the lower portiononly of a pipe and a low center of gravity and open at its upper end,means for pulling said sled through a pipe, upwardly facing spray meansfor producing a diffuse, foam-inducing spray, mounted on said sled andhaving upwardly directed nozzles for directing spray against the upperwalls only of said pipe, and

means for supplying a liquid aqueous mixture of phytocidal fumigant andsurfactant under pressure to said spray means so that a phytocidal foamcan be applied to the upper portions especially of said pipe.

2. The apparatus of claim I, wherein said nozzles are two in number,each directing upwardly at 45 from vertical on opposite sides of thevertical axis.

3. The apparatus of claim 1 wherein said sled supports valve means forturning on and turning off the flow of said spray means to said meansfor supplying liquid.

4. The apparatus of claim 3 having elongated means connected to saidvalve for remote operation thereof.

5. The apparatus of claim 1 having means spraying under pressure atabout to l25 psi.

6. The apparatus of claim 1 wherein the means for supplying includes areel of hose.

7. The apparatus of claim 1 wherein the means for pulling includes acoil spring cable and the means for supplying includes a conduit insidesaid cable.

8. The apparatus of claim 1 wherein the means for supplying includes ahose and the means for pulling includes a coil spring cable inside saidhose.

9. The apparatus of claim 8 wherein said coil spring cable is closewound and the hose is elastomer filling the space outside the coil.

1. Apparatus for treating root-infested sewer pipes including incombination a sled having a bottom skid for engaging the lower portiononly of a pipe and a low center of gravity and open at its upper end,means for pulling said sled through a pipe, upwardly facing spray meansfor producing a diffuse, foaminducing spray, mounted on said sled andhaving upwardly directed nozzles for directing spray against the upperwalls only of said pipe, and means for supplying a liquid aqueousmixture of phytocidal fumigant and surfactant under pressure to saidspray means so that a phytocidal foam can be applied to the upperportions especially of said pipe.
 2. The apparatus of claim 1, whereinsaid nozzles are two in number, each directing upwardly at 45* fromvertical on opposite sides of the vertical axis.
 3. The apparatus ofclaim 1 wherein said sled supports valve means for turning on andturning off the flow of said spray means to said means for supplyingliquid.
 4. The apparatus of claim 3 having elongated means connected tosaid valve for remote operation thereof.
 5. The apparatus of claim 1having means spraying under pressure at about 100 to 125 psi.
 6. Theapparatus of claim 1 wherein the means for supplying includes a reel ofhose.
 7. The apparatus of claim 1 wherein the means for pulling includesa coil spring cable and the means for supplying includes a conduitinside said cable.
 8. The apparatus of claim 1 wherein the means forsupplying includes a hose and the means for pulling includes a coilspring cable inside said hose.
 9. The apparatus of claim 8 wherein saidcoil spring cable is close wound and the hose is elastomer filling thespace outside the coil.